In a centralized radio access network (C-RAN) environment with full duplex transmissions, or asynchronous time-division duplexing to emulate full-duplex communication over a half-duplex communication link, signals transmitted by user equipment (UE) and received by remote radio heads (RRHs) are sent to a network node (“uplink communications”), such as a network operations center, for centralized processing. The directional communication link from a remote radio head to the network node is typically a fiber optic cable that requires enough bandwidth to transmit the signals that are received wirelessly at that RRM to the central network node.
The RRHs typically have both transmit and receive capabilities, though in some cases separate RRHs may be used for each function. For transmit operations where signals are transmitted by the RRHs to UE (“downlink communications”), the RRHs receive the outgoing signal from a network node, and carry out localized processing as required to prepare the signal for broadcast. In many cases the outgoing signal is prepared at the same network operations center that processes the received signals.
Due to the nature of downlink communications, a variety of methods are used to reduce the bandwidth of the downlink communications between the network node that generates the transmit signal, and the RRHs that prepare and broadcast the signal. These methods take advantage of the controlled system between the network node and the RRH, as well as the controlled operations of the RRH in preparing and broadcasting the signal.
A difficulty with uplink communications is that until the received signal is processed, it includes interference and noise. Generally, it is preferred to perform the some or all of the signal processing at the network node. Accordingly, uplink communications are generally transmitted from the RRH to the network node with only limited bandwidth reduction.
This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.